Modeling of stationary regimes of convective grain drying in the dense mobile layer

Currently, the market of grain dryers offers mainly convective dryers, realizing a continuous operating principle in a dense mobile layer. The process of grain drying is non-linear with divided parameters, most of the designs of grain dryers and their control systems are oriented to linear process and scalar control. The existing contradictions between the grain dryer (as an object with distributed parameters) and the management system of this object (based on the model with concentrated parameters) do not allow to optimize the drying processes. Based on the completed theoretical analysis of the balance equations of the interconnected heat and moisture exchange, a nonlinear mathematical model of drying process dynamics was constructed. A mathematical model is constructed, the distinguishing feature of which is the absence of hard-to-measure (partial water vapor pressure) and rapidly variable (moisture content of the drying agent) variables; taking into account the non-linear nature of the interaction between the dried grain and the drying agent in the interconnected processes of heat and moisture transport; simulation of the variables of traditional physical coefficients of heat and mass transfer by constant model coefficients, concerning the nature of their variation, depending on the speed of drying. A nonlinear mathematical model of the interconnected heat and moisture exchange between the drying agent and the grain layer is constructed. The rational parameters of the grain drying process are presented, which are optimal on the part of the efficiency criterion.